1. Field of the Invention
The present invention relates to a display device, a display method, and a program suitable for displaying images, characters, and other information on a display screen while showing a background scene through the display.
2. Description of the Related Art
There have been developed display devices having a transparent display that displays graphics, characters, and other information on a screen, while showing a background scene through the display. Such a transparent display sometimes uses a polymer-dispersed liquid crystal (also referred to as a polymer network liquid crystal, and may be referred to below simply as a liquid crystal). The liquid crystal has a characteristic to disperse an incident light when a voltage is not applied to the liquid crystal and transmits the light as it is when the voltage is applied, which is suitable for transparent displays.
FIG. 8 schematically shows a transparent display 100 in use.
The transparent display 100 is disposed in a display device (not shown) and displays graphics, characters, and other information, as well as the background scene, in rectangular frames in a display area 102. A screen of the transparent display 100 is formed with a plurality of dots, where, when the voltage applied to the liquid crystal corresponding to each dot is turned on and off, a dot applied with the voltage becomes transparent, and a dot not applied with the voltage becomes opaque. When a standby mode for making the screen of the transparent display 100 transparent is set, a background scene 101 is shown on a display area 104 through the transparent display 100. On the other hand, when an information display mode for making the screen of the transparent display 100 opaque is set, graphics, characters, and other information are displayed on an opaque display area 103. Hereinafter, the standby mode or the information display mode may be referred to simply as the mode.
During the standby mode, the screen does not become transparent unless the voltage keeps being applied to the liquid crystal. However, the liquid crystal has a characteristic that molecules are aligned at the moment the voltage is applied but dispersed as the voltage level lowers over time, resulting in an opaque screen. Therefore, by retaining an aligned state of the liquid crystal by switching the voltage applied to the liquid crystal corresponding to each dot between positive and negative at a predetermined display frame rate (for example, 60 frames/second), the transparent state can be retained to transmit the background scene through the screen.
Japanese Unexamined Patent Application Publication No. 2001-188499 discloses a technology of reducing a power consumption by generating a binary display signal with a small power consumption to be output to a display unit in the standby mode.